JPH07200407A - Virtual storage system - Google Patents

Abstract

PURPOSE:To increase secondary storage capacity without increasing the size of a page descriptor. CONSTITUTION:Plural page tables 200 indicated with logical addresses 100 contain secondary storage device numbers for selecting one of plural secondary storage devices 300. When page absence information indicates 'page absence', a secondary storage device 300 indicated with a secondary storage device number is accessed with the page address paired with the page absence information. When the page absence information indicates 'page presence', a main storage device 400 is accessed by using the page address paired with the page absence information as a physical address.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a virtual storage system in an information processing device, and more particularly to a virtual storage system for managing a large capacity secondary storage device.

[0002]

2. Description of the Related Art In a conventional virtual memory system, a page table for converting a virtual address into a physical address is provided with management information for each page called a page descriptor, and the page descriptor stores the storage position in a secondary storage device. Was managing information.

[0003]

In the above-mentioned conventional virtual storage system, the total capacity of the secondary storage devices that can be managed is limited by the size of the page descriptor, and it is difficult to increase the capacity of the secondary storage device. there were. On the contrary, increasing the size of the page descriptor has a great influence on the size of the page table, so it is difficult to increase the size of the page descriptor itself.

[0004]

In order to solve the above-mentioned problems, the present invention is a virtual memory system for managing a virtual memory space, wherein the virtual memory space is divided into pages of a certain size. A main storage device that stores a copy, a plurality of secondary storage devices that store a storage space that is not stored in the main storage device in the virtual storage space that is divided for each page, and the main storage device that stores the page A main memory management table for managing each of the plurality of secondary storage devices, a secondary storage device number for identifying one of the plurality of secondary storage devices, and a plurality of page descriptors for managing the virtual storage space divided for each page. Each of the page descriptors includes a plurality of page tables, and page fault information indicating whether a virtual storage space divided for each page is stored in the main storage device, and When a virtual memory space divided for each page is stored in the main memory device, the physical address of the main memory device is held and the virtual memory space divided for each page is stored in the main memory device. If not, the page address information holding the address in the secondary storage device is included.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the virtual storage system of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 1, a virtual storage system according to an embodiment of the present invention includes a page table 200 designated by a logical address 100 and a main storage device 400.
And a main memory management table 5 for managing the main memory 400
00 and a plurality of secondary storage devices 300 that save the storage area that cannot be stored in the main storage device 400.

The logical address 100 is managed in units of a storage space of a certain size called a page. The logical address 100 is, for example, a segment address 110 and an intra-segment page address 12 as shown in FIG.
It consists of 0 and an in-page address 130. The segment address 110 is used to select one of the plurality of page tables 200, and the in-segment page address 120 is used to select a page in the selected page table. The in-page address 130 is the page address on the main storage device 400 or the secondary storage device 30.
It is used as the address within the page after the page address on 0 has been determined.

A plurality of page tables 200 exist in the system, and each page table manages a plurality of pages. Each page group assigned to each page table is called a segment. Corresponding to each of the plurality of pages in this segment, the page table 200 includes a page descriptor including page absence information and a page address. The page absent information of the page descriptor indicates whether or not the corresponding page exists in the main memory. In the present embodiment, "1" is set when it exists in the main memory and "0" when it is saved in the secondary storage, but it may be specified to be the opposite. Needless to say. The page address of the page descriptor stores the physical address in the main memory when the page exists in the main memory, and the secondary storage device address in the secondary storage device when the page does not exist. Is stored.

Further, each page table 200 has a secondary storage device number for selecting one from a plurality of secondary storage devices 300. Therefore, the actual position on the secondary storage device can be determined by combining this secondary storage device number and the above-mentioned secondary storage device address.

To select one from the plurality of page tables 200, the segment address shown in FIG. 2 is used, for example. Then, the selected page table 20
To select a page descriptor at 0, the page address within segment 120 is used.

The main storage device 400 is a storage device accessed by a processing device (not shown), and is accessed by a physical address for each page by the page table 200.

The main storage device management table 500 stores information for managing the main storage device 400. As one of the management information stored in the main storage device management table 500, a secondary storage device address when each page in the main storage device 400 is saved in the secondary storage device 300 is included.

The secondary storage device 300 is for evacuating an area of the virtual storage space area that could not be stored in the main storage device. There are a plurality of secondary storage devices 300 in the system, and which secondary storage device 300 should be accessed is determined by the secondary storage device number in the page table 200.

Next, the flow of storage access processing in the virtual storage system according to the embodiment of the present invention will be described.

Referring to FIG. 3, in the memory access according to the embodiment of the present invention, first, the page table 200 is set by the segment address 110 of the logical address 100.
Is selected (step 201). Then, the page descriptor in the page table 200 is selected according to the in-segment page address 120 of the logical address 100 (step 202).

In the page descriptor in the page table 200 selected by the above process, if the page absent information indicates "page exists"("1") (step 2)
03), the physical address of the main memory 400 is stored in the page address of the page descriptor. In this case, by using this physical address (step 209), the main memory 400 can be accessed (step 208).

In the page descriptor in the page table 200 selected by the above processing, if the page fault information indicates "page fault"("0") (step 203), the page of the page descriptor. The secondary storage device address in the secondary storage device 300 is stored in the address. In this case, which secondary storage device 300 is determined by the secondary storage device number of the page table (step 204). Then, the address in the secondary storage device is determined by the secondary storage device address stored in the page address of the page descriptor (step 205).

Subsequently, the relevant page of the secondary storage device 300 thus determined is transferred to the main storage device 400 (hereinafter referred to as page-in processing) (step 20).
6). Along with this page transfer, the page table 200
The corresponding page descriptor of is rewritten (step 207).
That is, the page absence information is set to "page exists"("1").
Then, the secondary storage device address stored in the page address of the page descriptor is set to the main storage management table 50.
After saving to 0, the physical address of the main storage device 400 is set to the page address of the page descriptor. afterwards,
The page transferred to the main memory 400 can be accessed (step 208).

Prior to the page-in processing, if there is no free space in the main storage device 400, the well-known technique LR is used.
It is necessary to select a page in the main storage device 400 by U control or the like and write it to the secondary storage device 300 (hereinafter referred to as page-out processing). At the time of this page-out processing, the secondary storage device 300 stored by using the secondary storage device address stored in the main storage management table 500 is used.
Write to. The secondary storage device address is stored in the page address of the page descriptor. Further, the page fault information of the page descriptor is set to "page fault"("0").

[0020]

As described above, according to the present invention, by storing the secondary storage device number for each page table, it is possible to secure the secondary storage on a separate secondary storage device for each segment. it can. This has the effect that the secondary storage capacity can be increased without increasing the size of the page descriptor.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a virtual storage system of the present invention.

FIG. 2 is an example of a logical address configuration according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating an operation of a storage access process of the virtual storage system according to the embodiment of this invention.

[Explanation of symbols]

 100 logical address 110 segment address 120 segment address 130 page address 200 page table 300 secondary storage device 400 main storage device 500 main storage device management table

Claims (2)

[Claims] 1. A virtual memory system for managing a virtual memory space, the main memory device storing a part of the virtual memory space divided into pages of a certain size, and the main memory device divided into pages. A plurality of secondary storage devices that store a storage space that is not stored in the main storage device in the virtual storage space, a main storage management table that manages the main storage device for each page, and the plurality of secondary storage devices. A virtual storage system including a plurality of page tables including a secondary storage device number for identifying one of the storage devices and a plurality of page descriptors for managing a virtual storage space divided for each page. . 2. Each of the page descriptors includes page absence information indicating whether or not a virtual storage space divided for each page is stored in the main storage device, and virtual information divided for each page. When the storage space is stored in the main storage device, the physical address of the main storage device is held, and when the virtual storage space divided for each page is not stored in the main storage device, the virtual storage space is stored in the main storage device. The virtual memory system according to claim 1, further comprising page address information that holds an address in the next memory device.